The answer is A.
The brain sends signals by chemical reactions that occur in the neurons to the muscle cells.
The muscle cells, after receiving the signals sent by brain, contract and expand necessarily to execute the action, in other words, it performs work.
Hope this helps you! :)
Use the concept of beat frequency to find the applicable final freqeuncy for 20Hz beat frequency.
Beat can be defined as 'the interference pattern between two sounds of slightly different frequencies0
The expression for beat frequency is given as

Where,
Final frequency
Initial frequency
The beat frequency for us is 25Hz and the initial frequency is 240Hz, then

Being an absolute value, two values are possible, both in addition and subtraction:

The two possible values are


the 4 resistor wired in series is equal to 0.639 ohms
Answer: Rolling Friction
Explanation:A rolling ball stops because the surface on which it rolls resists its motion. A rolling ball stops because of friction.
It's a tough question as to whether light is a wave or a particle..
The statement is FALSE. Not all types of waves need a medium to propagate. Light can travel without a medium.
Extra Information:
Light is a longitudinal wave, sound is transverse.
Longitudinal waves do not need a medium.
Transverse waves need a medium.
This is why, for example, in the vacuum of space, light travels from stars, but sound does not.